Continuous water heater



April 1967 w. c. STRANKO 3,315,735

CONTINUOUS WATER HEATER Filed April 26, 1965 I INVENIOA.

WILLIAM C. STRANKO AT T ORA/5Y5 United States Patent 3,315,735 CONTINUOUS WATER HEATER William C. Stranko, Monroeville, Pa., assignor to The Patterson-Kelley Co., Inc., East Stroudsburg, Pa. Filed Apr. 26, 1965, Ser. No. 450,838 4 Claims. (Cl. 165-408) This invention relates to water heating and storing equipment, sometimes referred to in the industry as storage water heaters; and more particularly to improvements in such equipment employing immersion heating type components.

conventionally, water heaters, whether of the single or multiple immersion heater types, must be temporarily taken out of service whenever it is required to Withdraw one or more of the heat-exchange units for repair or maintenance purposes. Furthermore, it is required that the heater tank must be just emptied or at least partially drained before the exchanger may be withdrawn. Hence, in the case of many installations, such as wherever a tank of substantial size is involved, large quantities of previously heated and/or treated (softened, neutralized, filtered, etc.) water may of necessity be wasted incidental to a repair or maintenance operation. In some cases as much as 10,000 gallons of previously heated and/or treated water may thus be involved, and this of course would result in serious economic loss.

It is an object of the present invention to provide an improved water heating and storage apparatus including an improved water circulating arrangement relative to separately functionable immersion heater components, and control means therefore; whereby less than all of the immersion heaters of the system may be operative at a given time and whereby the inoperative heater or heaters may be easily withdrawn from the tank for heater repair and/or maintenance purposes, without interfering with normal overall operation of the apparatus.

Another object is to provide an improved waterheating and storing apparatus of the type referred to, featuring the provision of a pluralityof immersion heaters in conjunction with a single storage tank and a novel water circulation system in conjunction therewith, whereby an improved and uniform water temperature control response is attainable both under normal and peak hot water demand conditions.

Another object is to provide an improved apparatus as aforesaid which is adapted to automatically supply the desired quantities of water at the desired temperatures while drawing upon heat supplies only as needed, in order to efficiently comply with the heated water demands. Still another object is to provide an improved system as aforesaid which may be operated to adapt it to efficiently supply hot water at the desired temperature under a wide variety of volume load conditions.

Other objects and advantages of the invention will appear from the specification hereinafter and the accompanying drawings wherein:

FIG. 1 is a longitudinal vertical section through one example of a water storage heater system of the invention;

FIG. 2 is a front end elevational view thereof; and

FIG. 3 is a fragmentary view illustrating an alternative positional arrangement of the temperature sensor and heat "ice interior of the tank 10 and are welded thereto as indicated at 18. The shrouds are closed at their inner ends as indicated at 19 (FIG. 1).

At their outer ends the shrouds 16, 17 are flanged and carry tube sheets 20, 21 through which the open ends of the tubes extend into open communication with the interior chambers of horizontally partitioned bonnets 22, 23 which are similarly flanged and bolted in cooperation with the tube sheets to the ends of the shrouds 16, 17. Thus, the steam or other heating fluid may be introduced as by means of conduits 24, 25 into the upper portions of the bonnets, from whence it flows through the return bent tubes and then into the lower portions of the bonnets for discharge through condensate traps or the like as indicated at 26, FIG. 1. Passage of steam through the conduits 24, 25 and into the respective heating systems may be controlled as by means of any suitable flow regulators or the like, as indicated at 28 which are in turn controlled by a temperature sensing bulb or the like. As shown in FIG. 1 the sensing bulb 30 may be located in the hot water storage area, and the hot water take-off conduit is shown at 32.

Leading into the outer end of each tube shroud is a water circulating conduit as shown at 34, which in each case connects to a constantly running pump 36 delivering through a conduit 37. In each case the tube shrouds are fitted with outlet conduits adjacent their closed inner ends, as shown for example at 38, 39 which join to deliver into a hot water spreader or manifold such as may comprise an apertured pipe which extends substantially into the lower length of the storage tank but above the tank bottom and the level of the cold water inlet 12. Hence, operation of the pump 36 draws water along the lower level of the tank from the inlet 12 and delivers it as indicated by the flow directional arrows of FIG. 1, first into the outer ends of the heater shrouds 16, 17 and thence through the conduits 38, 39 into the manifold 40 from which it flows in the form of widely spread out dispersions of heated water into the body of the tank. Alternatively to the arrangement of FIG. 1 the temperature sensing bulb 30 may be perhaps more advantageously located (as shown in FIG. 3) in the stream of water entering the manifold 40.

Note that the direction of water flow through the shrouds 16, 17 is such as to first bring the feed water from the tank into the outer end of the shroud and into heatexchange contact with the relatively hotter portions of the tube bundles. Thence the water travels in heat exchange relationship With the tubes 14, 15 until it reaches the outlet conduits 38, 39, and it then passes into the manifold 40 and out into the body of the tank 10. Thus, it will be appreciated that whenever 'heated water is drawn from the outlet 32, fresh water will automatically flow through the inlet 12, and into the bottom interior of the tank 10. From thence it is drawn by the pump 36 and discharged through the conduit 37 into' the branch conduits 34,, 35, and thence into the heat exchange casings 16, 17. Then, as previously explained, the heated water flows out of the heater casings through the conduits 38, 39 and the manifold 40 into the interior of the tank, thereby replacing the water drawn from the outlet 32. As the sensor 30 detects undesirable lowering of the temperature of the water moving into the body of the tank it operates through control conduits 42, 44, to actuate the steam inlet control regulators 23, whereby it will be understood that the temperature of the water in the tank is automatically controlled within the desired upper and lower temperature limits.

As shown in the drawing herewith, the system may preferably include a water temperature drop anticipator arrangement in combination with the temperature sensor 30. In this case, a cold water bypass conduit as indicated at 46 is tapped into the pump discharge conduit 37 and leads into the sensor shroud as indicated at 48 (FIG. 2). Thus, whenever water is withdrawn from the outlet 32, the reduced pressure inside the tank sets up a reduced pressure condition inside the sensor shroud and the connection 48, whereby relatively cool water is immediately drawn through the bypass conduit 46 into the outer end of the shroud surrounding the sensor 30. This cool water then flows through the shroud in heat exchange relation with the sensor bulb, thereby causing the latter to more quickly indicate need for more heat supply, than would otherwise be the case. An anticipator system of this type is disclosed and explained for example in greater detail in US. Patent No. 3,133,590, and of course may be employed in conjunction with either the sensing bulb arrangement shown in FIG. 1 Orin FIG. 3.

In accordance with the present invention, the heating units are arranged to be functionally segregated, and electively operated as required and/or desired. To this end the conduits 34, 35, which direct cool water to the respective heaters, are furnished with corresponding control valves 50, 52; and the hot water recirculation conduits 38, 39, are similarly provided with corresponding control valves 54, 56. Thus, it will be appreciated that either one of the heating units may be rendered inoperative by simply closing off its steam supply and the inlet and outlet valves thereof, without interfering with operation of the other heater unit. Hence, the arrangement permits the withdrawal of any one heating element from its casing (simply by unbolting its bonnet and withdrawing the tube bundle) wtihout requiring emptying of the main tank, thereby avoiding any necessity for idling the other heating elements, as in the case of the prior art' As shown at 60, each shroud 16 is preferably provided with an external 'drain cock, permitting emptying of the shroud of its water content after the appropriate valves are closed and before removing the bonnet 22.

The heating components of the system should be sized to pass the highest peak load of water withdrawal rate expected on the system with a nominal pressure drop. Also, they should be sized for either the recovery capacity required or balanced out at a specific rate so that when matched with the amount of hot water held in reserve, they will be able to furnish the required amount of water through the duration of the peak-load. Thus, whenever one of the heater units is out for repair a constant temperature will prevail at all times in the tank, and the storage supply will adequately meet the major part of the total peak demand with the balance being taken care of by the operative heating element or elements as the water passes therethrough.

It will thus be appreciated that the device of the invention may be readily constructed in unit form, fully selfcontained and requiring minimum floor space, and it is therefore suitable for installation in out-of-way locations. It may readily be connected into existing piping systems, and normally draws upon the associated steam generating boiler in such limited manner as to avoid interference with constant steam pressure at the associated steam operated equipment, if any. Hence, the boiler load is leveled off, thereby improving its efliciency and life span.

It will of course be appreciated that although only one form of the invention has been illustrated and described in detail hereinabove, various changes may be made therein without departing from the spirit of the invention or the scope of the following claims. For example, whereas the heat supply devices illustrated and described hereinabove are of the return-bent tube bundle type employing steam as the heat source, it will be appreciated that in lieu thereof hot water or other fluid or gas may be employed, and that the heat exchange mechanisms may be of any other suitable type. Or, the heating elements may be of the electric-resistance or inductive heating type,- as may be preferred.

Also, it will be understood that whereas only two heat exchange components have been illustrated and described in detail hereinabove, any other desired number of heater components may be employed. The number of temperature sensors and the number of pumps employed in conjunction with the conduit system providing for constant circulation of water through the (operable) heaters will also be a matter of engineering choice, In some cases a single pump and a single sensor may be suitably arranged to accommodate a multiple heater system of the invention, while in other intsances it may be preferred for example to provide a pump and a sensor in conjunction with each of the heater components of the system. In any case, the conduits providing for flow of water into and out of the opposite ends of the heater shrouds are arranged to be controlled by separate valves so that at any time the interiors of one or more of the shrouds may be isolated from the water circulating system which is in communication with the interior of the tank; whereby the shroud may be opened at its outer end for heater maintenance purposes without interfering with operation of the balance of the system.

I claim:

1. A water heating system comprising, essentially,

a single water carrying storage tank,

a plurality of emersion heaters extending into said tank,

each said emersion heaters comprising a shroud projecting through a wall portion of said tank and extending both inwardly and outwardly therefrom and being closed at its inner extending portion,

a cool water inlet connection into the outer end of each said shroud,

a hot water outlet connection into the inner extending end portion of each said shrouds,

a tube sheet closing the extreme outer ends of each said shrouds,

a bundle of return-bent tubes mounted upon each of said tube sheets and disposed within each of said shrouds,

means circulating heating fluid through said tubes,

a cold water inlet connection into the bottom portion of said tank,

and a storage water constant circulation device comprising pump means and a conduit system operable for circulating the water enclosed in the system to flow outwardly through the outlet connections at the inner ends of each said shrouds and thence into the body of said tank and thence from out of the bottom section of said tank and through said inlet connections into the interiors of said shrouds,

and valve means associated with said conduit system being controllable to isolate any one of said heater shrouds from the water circulating system whereby the' isolated shroud may be opened at its outer end and its tube bundle withdrawn without loss of pressure and/or interference with operation of .the balance of the system.

2. A water heating system comprising,

a water storage tank,

an emer-sion heater extending into said tank,

said emersion heater comprising an elongate shroud projecting through a wall portion of said tank and extending both inwardly and outwardly therefrom, and being closed at its inner end,

a hot water supply outlet conduit connected into the inner extending end portion of said shroud and arranged to deliver into the body of said tank,

a tube sheet closing the outer end of said shroud,

a plurality of heat exchange tubes mounted upon said tube sheet and disposed within said shroud substantially throughout the length thereof,

means supplying heating fluid to said tubes,

a cold Water inlet conduit connected for delivery into the outer end portion of said shroud, 1 I

and a storage water circulation device comprising a pump drawing water from the bottom level of said tank and delivering it through said inlet conduit into said shroud and thereby forcing heated Water to discharge through said outlet conduit into said tank, and valve devices associated with each of said inlet and outlet conduits and adapted to be closed to isolate the interior of said shroud from fluid-flow communication with the interior of said tank.

3. A Water heating system comprising,

a water storage tank,

a plurality of emersi-on heaters extending into said'tank,

said ernersion heaters each comprising an elongate shroud projecting through a wall portion of said tank and extending both inwardly and outwardly therefrom, and being closed at its inner end,

a hot water outlet conduit connected into the inner extending end portion of each said shroud and arranged to deliver into the body of said tank,

a bonnet closing the outer end of each of said shrouds,

a heat supply device disposed within each said shrouds,

a cold water inlet conduit connected for delivery into the outer end portion of each of said shrouds,

a storage water circulation device comprising a pump drawing Water from the bottom level of said tank and delivering it through said inlet conduits into said shrouds and thereby forcing heated water to discharge through said outlet conduits into said tank,

and valve devices associated with each of said inlet and outlet conduits and adapted to be closed to isolate the interior of any one of said shrouds from fluid-flow communication with the interior of said tank.

4. A water heating system comprising,

a water storage tank,

a plurality of ernersion heaters extending into said tank,

said ernersion heaters each comprising a shroud extending into said tank and being open to the exterior of said tank and being closed at its inner extending end,

a hot water outlet conduit connected in communication with the inner extending end portion of each of said shrouds and arranged to deliver into the body of said tank,

detachable cover means normally closing the outer open end portion of each of said shrouds to provide each of closed vessel form,

a heat supply device disposed within each said shrouds,

a cold water inlet conduit connected for delivery into the outer end portion of each of said shrouds,

a storage water circulation device comprising a pump drawing water from a water supply and delivering it through said inlet conduits into said shrouds and thereby forcing heated water to pass through said outlet conduits into said tank,

and control means associated with said conduits and adapted to be regulated so as to electively isolate the interior of any one of said shrouds from fluid-flow communication with the interior of said tank.

References Cited by the Examiner UNITED STATES PATENTS 1,705,574 3/ 1929 Klingemann 165l08 3,053,516 9/ 1962 Killebrew 16539 3,133,590 5/1964 Lowe 16539 FOREIGN PATENTS 968,524 2/ 1958 Germany.

FREDERICK L. MATTESON, JR., Primary Examiner.

35 R. A. DUA, Assistant Examiner. 

4. A WATER HEATING SYSTEM COMPRISING, A WATER STORAGE TANK, A PLURALITY OF EMERSION HEATERS EXTENDING INTO SAID TANK, SAID EMERSION HEATERS EACH COMPRISING A SHROUD EXTENDING INTO SAID TANK AND BEING OPEN TO THE EXTERIOR OF SAID TANK AND BEING CLOSED AT ITS INNER EXTENDING END, A HOT WATER OUTLET CONDUIT CONNECTED IN COMMUNICATION WITH THE INNER EXTENDING END PORTION OF EACH OF SAID SHROUDS AND ARRANGED TO DELIVER INTO THE BODY OF SAID TANK, DETACHABLE COVER MEANS NORMALLY CLOSING THE OUTER OPEN END PORTION OF EACH OF SAID SHROUDS TO PROVIDE EACH OF CLOSED VESSEL FORM, A HEAT SUPPLY DEVICE DISPOSED WITHIN EACH SAID SHROUDS, A COLD WATER INLET CONDUIT CONNECTED FOR DELIVERY INTO THE OUTER END PORTION OF EACH OF SAID SHROUDS, A STORAGE WATER CIRCULATION DEVICE COMPRISING A PUMP DRAWING WATER FROM A WATER SUPPLY AND DELIVERING IT THROUGH SAID INLET CONDUITS INTO SAID SHROUDS AND THEREBY FORCING HEATED WATER TO PASS THROUGH SAID OUTLET CONDUITS INTO SAID TANK, AND CONTROL MEANS ASSOCIATED WITH SAID CONDUITS AND ADAPTED TO BE REGULATED SO AS TO ELECTIVELY ISOLATE THE INTERIOR OF ANY ONE OF SAID SHROUDS FROM FLUID-FLOW COMMUNICATION WITH THE INTERIOR OF SAID TANK. 